This patch-set introduces the possibility of protecting memory that has been allocated dynamically.
The memory is managed in pools: when a memory pool is turned into R/O, all the memory that is part of it, will become R/O. A R/O pool can be destroyed, to recover its memory, but it cannot be turned back into R/W mode. This is intentional. This feature is meant for data that doesn't need further modifications after initialization. However the data might need to be released, for example as part of module unloading. To do this, the memory must first be freed, then the pool can be destroyed. An example is provided, in the form of self-testing. Changes since v16: [http://www.openwall.com/lists/kernel-hardening/2018/02/12/13] * introduced lkdtm test for write protection of a variable * added comments with rationale for use of BUG_ON() when running selftest * converted self-tests to kernel naming patter "test_xxx.c" * moved triggering of pmalloc self-testing to early phase of main.c * improved summaries of genalloc and vmalloc patches * removed example of optimization of find_vm_area because of possible bug in vmalloc_to_page: [https://email@example.com/msg1617030.html] Igor Stoppa (7): genalloc: track beginning of allocations genalloc: selftest struct page: add field for vm_struct Protectable Memory Pmalloc selftest lkdtm: crash on overwriting protected pmalloc var Documentation for Pmalloc Documentation/core-api/index.rst | 1 + Documentation/core-api/pmalloc.rst | 114 +++++++ drivers/misc/lkdtm.h | 1 + drivers/misc/lkdtm_core.c | 3 + drivers/misc/lkdtm_perms.c | 28 ++ include/linux/genalloc.h | 7 +- include/linux/mm_types.h | 1 + include/linux/pmalloc.h | 242 ++++++++++++++ include/linux/test_genalloc.h | 26 ++ include/linux/test_pmalloc.h | 24 ++ include/linux/vmalloc.h | 1 + init/main.c | 4 + lib/Kconfig | 15 + lib/Makefile | 1 + lib/genalloc.c | 658 +++++++++++++++++++++++++++---------- lib/test_genalloc.c | 410 +++++++++++++++++++++++ mm/Kconfig | 15 + mm/Makefile | 2 + mm/pmalloc.c | 499 ++++++++++++++++++++++++++++ mm/test_pmalloc.c | 79 +++++ mm/usercopy.c | 33 ++ mm/vmalloc.c | 5 + 22 files changed, 1999 insertions(+), 170 deletions(-) create mode 100644 Documentation/core-api/pmalloc.rst create mode 100644 include/linux/pmalloc.h create mode 100644 include/linux/test_genalloc.h create mode 100644 include/linux/test_pmalloc.h create mode 100644 lib/test_genalloc.c create mode 100644 mm/pmalloc.c create mode 100644 mm/test_pmalloc.c -- 2.14.1